servo: Add control to probe the EC board via EC console

Get the EC board by sending EC command "ver" on console and parse
its result.

BUG=b:37473185
TEST=Tested on servo v2 and servo v4, dut-control ec_board

Change-Id: I21fdc2036ddb04032f166f975acce26b6c31bc48
Reviewed-on: https://chromium-review.googlesource.com/509959
Commit-Ready: Wai-Hong Tam <waihong@google.com>
Tested-by: Wai-Hong Tam <waihong@google.com>
Reviewed-by: Aseda Aboagye <aaboagye@chromium.org>
2 files changed